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Using a result of Robertson \textit{[Proc. Edinburgh Math. Soc. (2), 1976]}, we introduce a notion of differentiation of maps on certain classes of unital commutative C*-algebras. We then derive C*-algebraic Gauss-Lucas theorem and…

Operator Algebras · Mathematics 2026-04-03 K. Mahesh Krishna

We prove that if $f:(a,b)\to\mathbb{R}$ is convex, then for any $\varepsilon>0$ there is a convex function $g\in C^2(a,b)$ such that $|\{f\neq g\}|<\varepsilon$ and $\Vert f-g\Vert_\infty<\varepsilon$.

Classical Analysis and ODEs · Mathematics 2025-11-11 Paweł Goldstein , Piotr Hajłasz

We prove a conjecture of B. Gr\"unbaum stating that the set of affine invariant points of a convex body equals to the set of points invariant under all affine linear symmetries of the convex body. As a consequence we give a short proof on…

Metric Geometry · Mathematics 2017-09-11 Olaf Mordhorst

In this paper, we establish some new Hadamard type inequalities for s-logarithmically convex functions in the second sense via fractional integrals by using Lemma 1 which has been proved by Sarikaya et al. in the paper [3].

Functional Analysis · Mathematics 2012-12-10 Havva Kavurmaci , Mevlut Tunc

In this paper we give a new proof for an almost isometry theorem in Alexandrov spaces with curvature bounded below.

Differential Geometry · Mathematics 2010-06-29 Xiaole Su , Hongwei Sun , Yusheng Wang

New proofs of the Hadwiger theorem for smooth and for continuous valuations on convex functions are obtained, and the Klain-Schneider theorem on convex functions is established. In addition, an extension theorem for valuations defined on…

Functional Analysis · Mathematics 2023-01-02 Andrea Colesanti , Monika Ludwig , Fabian Mussnig

In his work on log-concavity of multiplicities, Okounkov showed in passing that one could associate a convex body to a linear series on a projective variety, and then use convex geometry to study such linear systems. Although Okounkov was…

Algebraic Geometry · Mathematics 2008-05-30 Robert Lazarsfeld , Mircea Mustata

We give an alternative proof of a recent result of Klartag on the existence of almost subgaussian linear functionals on convex bodies. If $K$ is a convex body in ${\mathbb R}^n$ with volume one and center of mass at the origin, there exists…

Functional Analysis · Mathematics 2007-05-23 Apostolos Giannopoulos , Alain Pajor , Grigoris Paouris

In this paper we show that, in the definition of Alexandrov spaces with lower or upper curvature bound, the original conditions can be replaced with much weaker ones. For the purpose, we introduce `imaginary' comparison angles (and…

Differential Geometry · Mathematics 2023-08-30 Shengqi Hu , Xiaole Su , Yusheng Wang

We analyze matrix convex functions of a fixed order defined on a real interval by differential methods as opposed to the characterization in terms of divided differences given by Kraus. We obtain for each order conditions for matrix…

Operator Algebras · Mathematics 2007-05-23 Frank Hansen , Jun Tomiyama

Alexandrov spaces are defined via axioms similar to those given by Euclid. The Alexandrov axioms replace certain equalities with inequalities. Depending on the signs of the inequalities, we obtain Alexandrov spaces with curvature bounded…

Differential Geometry · Mathematics 2023-06-13 Stephanie Alexander , Vitali Kapovitch , Anton Petrunin

In his book on Convex Polyhedra (section 7.2), A.D. Aleksandrov raised a general question of finding variational statements and proofs of existence of polytopes with given geometric data. The first goal of this paper is to give a…

Differential Geometry · Mathematics 2007-05-23 Vladimir Oliker

The hermitian analog of Aleksandrov's area measures of convex bodies is investigated. A characterization of those area measures which arise as the first variation of unitarily invariant valuations is established. General smooth area…

Differential Geometry · Mathematics 2013-07-16 Thomas Wannerer

This is a survey paper on various results relates to the following theorem first proved by A.D. Alexandrov: \textit{Let $S$ be an analytic convex sphere-homeomorphic surface in $\mathbb R^3$ and let $k_1(\boldsymbol{x})\leqslant…

Differential Geometry · Mathematics 2012-12-21 Victor Alexandrov

The Alexandrov-Fenchel inequality, a far-reaching generalization of the classical isoperimetric inequality to arbitrary mixed volumes, lies at the heart of convex geometry. The characterization of its extremal bodies is a long-standing open…

Metric Geometry · Mathematics 2022-02-04 Yair Shenfeld , Ramon van Handel

We use the intrinsic area to define a distance on the space of homothety classes of convex bodies in the $n$-dimensional Euclidean space, which makes it isometric to a convex subset of the infinite dimensional hyperbolic space. The ambient…

Differential Geometry · Mathematics 2021-09-02 Clément Debin , François Fillastre

Proceeding the study of local properties of analytic functions started in [Br] we prove new dimensionless inequalities for such functions in terms of their Chebyshev degree. As a consequence, we obtain the reverse Holder inequalities for…

Complex Variables · Mathematics 2007-05-23 A. Brudnyi

This work is concerned with a P\'olya-Szeg\"o type inequality for anisotropic functionals of Sobolev functions. The relevant inequality entails a double-symmetrization involving both trial functions and functionals. A new approach that…

Functional Analysis · Mathematics 2025-01-03 Gabriele Bianchi , Andrea Cianchi , Paolo Gronchi

In ["Illumination of convex bodies with many symmetries", Mathematika 63 (2017)], Tikhomirov verified the Hadwiger-Boltyanski Illumination Conjecture for the class of 1-symmetric convex bodies of sufficiently large dimension. We propose an…

Metric Geometry · Mathematics 2024-07-16 Wen Rui Sun , Beatrice-Helen Vritsiou

Distance functions of metric spaces with lower curvature bound, by definition, enjoy various metric inequalities; triangle comparison, quadruple comparison and the inequality of Lang-Schroeder-Sturm. The purpose of this paper is to study…

Differential Geometry · Mathematics 2009-12-02 Takumi Yokota